Dialyzable Leukocyte Extract

ProteinTransfer factor

What is it

Dialyzable leukocyte extract (DLE), also called transfer factor, is a mixture of low-molecular-weight peptides obtained by dialysis from disrupted white blood cells (leukocytes), historically from bovine sources.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Recurrent viral infections (limited evidence)

Limited Evidence

Small clinical studies in herpes simplex, mucocutaneous candidiasis, and some other conditions suggest possible benefits. Evidence is heterogeneous and not widely accepted in mainstream practice.

How it works

DLE is hypothesized to transfer cell-mediated immune information between donor and recipient. Mechanism remains controversial; the specific active components and pathways are not fully characterized. Some clinical studies have explored DLE for chronic viral infections, recurrent infections, and immune modulation.

Dosage

No standardized dose. Clinical studies have used variable amounts of bovine or porcine DLE based on protein content. Supplement labels are inconsistent.

When and how to take it

No standard timing. Oral DLE supplements follow product directions.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Oral capsule or sublingual tablet

Marketed widely as 'transfer factor' supplements.

Peptide stability and absorption are limited

Safety

DLE has been used clinically in some countries (notably Mexico) for decades with reasonable tolerability reports. Allergic reactions and injection-site reactions (for parenteral use) are possible. Quality control varies.

Who should be cautious

Avoid in pregnancy, breastfeeding, autoimmune disease, organ transplant immunosuppression, and severe immunodeficiency unless directed by a specialist.

Interactions

Potential additive effects with immunomodulatory medications. Discuss with a clinician before combining.

Frequently asked questions

What is transfer factor?⌄

Another name for dialyzable leukocyte extract: a peptide mixture from white blood cells used in some immune-support supplements.

Is it FDA-approved?⌄

No. DLE is sold as a dietary supplement in the US, not as an approved drug.

References

Dialyzable Leukocyte Extract on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Dialyzable Leukocyte Extract (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.